This invention relates to a method of xe2x80x9cfinishingxe2x80x9d a golf ball and, in particular, preparing a golf ball to receive indicia, creating a digital image of the indicia, and directly printing the image on the dimpled surface of the golf ball.
More than five hundred million golf balls are produced each year, a significant percentage of which have indicia or logos printed on their outer surface. The indicia typically include any one of the golf ball company, tradename, a number, or an image, such as a corporate or country club logo. The most common method for adding a logo to the dimpled surface of a golf ball is by pad printing, although other methods, such as inkjet printing, are adaptable for such surfaces.
The pad printing process begins by spreading ink across the surface of a pad printing clichxc3xa9 or xe2x80x9cplatexe2x80x9d containing etched or depressed version of the desired image. Ink is dispersed over the etched area and excess ink is removed with a xe2x80x9cdoctorxe2x80x9d blade or cup. Upon exposure to air, thinner evaporates from the ink causing it""s surface to become xe2x80x9ctacky.xe2x80x9d A smooth, resilient, block of silicone rubber (the xe2x80x9cpadxe2x80x9d) is brought into contact with the tacky surface of the ink. As the pad is withdrawn from the plate surface, an adhering film of ink is transferred to the pad. The ink is carried on the pad to the target area on the golf ball surface, during which time thinner in the ink further evaporates, causing the exposed ink surface on the pad to become tacky. Upon contact with the golf ball surface, the film of ink is transferred from the pad to the ball surface.
Pad printing plates are typically stiff plates coated with a photopolymer material that cures upon exposure to UV light. The etched version of the image is formed by placing a film positive of the image over the plate and irradiating the surface with UV light. In this manner, the exposed areas of the plate harden, while blocked areas remain soft. The soft polymer is then removed by a series of washing steps, creating etched areas correlating to the logo.
The pad printing process, however, is not without limitations. Creating the etched plates is a time-consuming process involving many steps. Commercially-available photopolymer plates all require the use of chemicals in many of the steps and a variety of solvents, including alcohols, for the washing steps. Further, the plates must be created within a finite time prior to printing, each spot color in the image or selected color space requires a separate plate, and the depth of etch in each plate can be difficult to control. When a new image is desired, the entire process of creating an etched plate for each color must be repeated. Finally, the clean up of plate materials, chemicals, inks, and printing machines, can be exhaustive, and requires strict compliance with a variety of environmental regulations.
It would be desirable, therefore, to develop a method for xe2x80x9cfinishingxe2x80x9d a golf ball and simply and efficiently creating printed indicia on the ball directly from a digital image. Further, it would be desirable to couple this method with pad printing or inkjet printing for parallel, digital xe2x80x9ccomputer-to-pressxe2x80x9d printing of indicia concurrently with the finishing of a golf ball.
The present invention is directed to a method for finishing a golf ball comprising the steps of providing a golf ball having a three-dimensional dimpled surface; preparing the surface for receiving at least one indicia; providing a digital image having at least one color; providing a multi-layered pad-printing substrate having at least one layer; etching the image into the at least one layer of the substrate with a laser; distributing a layer of ink over the etched substrate; providing at least one pad for transferring the ink from the substrate to the three-dimensional surface; and transferring the image from the substrate to the dimpled surface of the golf ball.
The step of preparing the surface for receiving at least one indicia further typically includes buffing, sand blasting, and/or plasma treating the dimpled surface of the golf ball. If desired, the golf ball may be primed and/or top coated subsequent to printing the indicia. Generally, the digital image will include a plurality of colors. If so, the colors are then separated into the individual colors of a predetermined color space. Each individual color of the predetermined color space, therefore, should has an associated pad printing substrate.
The color space is selected from the group consisting of CMYK color space, CMYKOG color space, 4-color color space, 6-color color space, 8-color color space, 12-color color space, or a mixture thereof. It is preferred that the color space is CMYK.
The at least one pad printing substrate preferably includes a flexible, photopolymeric material and, more preferably, includes at least two layers. The first layer is preferably a flexible opaque layer and a second layer is preferably a flexible base layer. The first opaque layer has a thickness of less than about 5 xcexcm, preferably, from about 5 xcexcm to about 40 xcexcm, and more preferably, from about 15 xcexcm to about 25 xcexcm.
The second flexible base layer includes at least one of polyester, polyethylene, or a mixture thereof. The laser includes a continuous wave laser, a pulsed laser, a solid state laser, a gas laser, or an excimer laser or, if multiple lasers are used, any combination thereof. The laser emits at a preselected wavelength and, preferably, the at least one laser is a pulsed laser. The pulsed laser should have a power greater than about 20 mW/pulse to sufficiently etch the flexible substrate. If desired, the color separation(s), if more than one are present, may be etched using at least two lasers.
The etched image preferably has a depth of less than about 0.0016 inches, more preferably, from about 0.0004 inches to about 0.0016 inches, and most preferably, from about 0.0006 inches to about 0.0010 inches. The thickness of the ink layer on the golf ball is from about 4 xcexcm to about 50 xcexcm, preferably, from about 4 xcexcm to about 20 xcexcm. Ideally, the ink on the three-dimensional surface requires no more than about 30 seconds to cure.
The present invention is also directed to a method for finishing a golf ball comprising the steps of providing a golf ball having a three-dimensional dimpled surface; preparing the surface for receiving at least one indicia; providing a digital image having at least one color; transferring the image to the surface with an inkjet head; and treating the surface with a coating comprising a clear coat, a top coat, a primer, or a mixture thereof. Additionally, the step of preparing the surface for receiving at least one indicia further should include at least one of buffing, sand blasting, or plasma treating the dimpled surface. The digital image includes a plurality of colors which, if necessary, are separated into the individual colors of a predetermined color space. If so, the color space can be a CMYK color space, CMYKOG color space, 4-color color space, 6-color color space, 8-color color space, 12-color color space, or a mixture thereof. Preferably, the color space is CMYK. The ink on the three-dimensional surface should cure in no more than about 30 seconds.
The image transferred by the inkjet head should have an ink thickness of about 4 xcexcm to about 50 xcexcm, preferably about 4 xcexcm to about 20 xcexcm. The image transferred by the inkjet head includes solvent evaporating inks, oxidation curing inks, reactive (catalyst curing or two-component) inks, baking inks, UV curable inks, sublimation inks, and ceramic and glass inks. The image transferred by the inkjet head may further include an additive, such as binders, reactive prepolymers, thinners, low-viscosity mono and poly-functional monomers, photoinitiators, stabilizing additives, flow control agents, wetting agents, pigments, extenders, or a mixture thereof.
The inkjet image may have at least one spot color, a plurality of different colors, a shading effect, a gradient of colors, or a mixture thereof. The step of treating the surface with a coating comprising a clear coat, a top coat, a primer can occur at any point in the process, however preferably occurs prior to transferring the image to the surface with the inkjet head. The image may be cured in a dry room, which may be at an elevated temperature, preferably at least about 40xc2x0 C. The printed golf balls are preferably kept in the dry room, when used, for at least about 4 hr.